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  <div class="SECT1">
    <h1 class="SECT1"><a name="CONFIG" id="CONFIG">7. The Main Configuration
    File</a></h1>

    <p>By default, the main configuration file is named <tt class=
    "FILENAME">config</tt>, with the exception of Windows, where it is named
    <tt class="FILENAME">config.txt</tt>. Configuration lines consist of an
    initial keyword followed by a list of values, all separated by whitespace
    (any number of spaces or tabs). For example:</p>

    <p class="LITERALLAYOUT"><tt class="LITERAL">&nbsp;&nbsp;<span class=
    "emphasis EMPHASIS c2">confdir /etc/privoxy</span></tt></p>

    <p>Assigns the value <tt class="LITERAL">/etc/privoxy</tt> to the option
    <tt class="LITERAL">confdir</tt> and thus indicates that the
    configuration directory is named <span class=
    "QUOTE">"/etc/privoxy/"</span>.</p>

    <p>All options in the config file except for <tt class=
    "LITERAL">confdir</tt> and <tt class="LITERAL">logdir</tt> are optional.
    Watch out in the below description for what happens if you leave them
    unset.</p>

    <p>The main config file controls all aspects of <span class=
    "APPLICATION">Privoxy</span>'s operation that are not location dependent
    (i.e. they apply universally, no matter where you may be surfing). Like
    the filter and action files, the config file is a plain text file and can
    be modified with a text editor like emacs, vim or notepad.exe.</p>

    <div class="SECT2">
      <h2 class="SECT2"><a name="LOCAL-SET-UP" id="LOCAL-SET-UP">7.1. Local
      Set-up Documentation</a></h2>

      <p>If you intend to operate <span class="APPLICATION">Privoxy</span>
      for more users than just yourself, it might be a good idea to let them
      know how to reach you, what you block and why you do that, your
      policies, etc.</p>

      <div class="SECT3">
        <h4 class="SECT3"><a name="USER-MANUAL" id="USER-MANUAL">7.1.1.
        user-manual</a></h4>

        <div class="VARIABLELIST">
          <dl>
            <dt>Specifies:</dt>

            <dd>
              <p>Location of the <span class="APPLICATION">Privoxy</span>
              User Manual.</p>
            </dd>

            <dt>Type of value:</dt>

            <dd>
              <p>A fully qualified URI</p>
            </dd>

            <dt>Default value:</dt>

            <dd>
              <p><span class="emphasis EMPHASIS c2">Unset</span></p>
            </dd>

            <dt>Effect if unset:</dt>

            <dd>
              <p><a href="http://www.privoxy.org/user-manual/" target=
              "_top">http://www.privoxy.org/<tt class=
              "REPLACEABLE c3">version</tt>/user-manual/</a> will be used,
              where <tt class="REPLACEABLE c3">version</tt> is the
              <span class="APPLICATION">Privoxy</span> version.</p>
            </dd>

            <dt>Notes:</dt>

            <dd>
              <p>The User Manual URI is the single best source of information
              on <span class="APPLICATION">Privoxy</span>, and is used for
              help links from some of the internal CGI pages. The manual
              itself is normally packaged with the binary distributions, so
              you probably want to set this to a locally installed copy.</p>

              <p>Examples:</p>

              <p>The best all purpose solution is simply to put the full
              local <tt class="LITERAL">PATH</tt> to where the <i class=
              "CITETITLE">User Manual</i> is located:</p>

              <table class="c4" border="0" width="90%">
                <tr>
                  <td>
                    <pre class="SCREEN">
  user-manual  /usr/share/doc/privoxy/user-manual
</pre>
                  </td>
                </tr>
              </table>

              <p>The User Manual is then available to anyone with access to
              <span class="APPLICATION">Privoxy</span>, by following the
              built-in URL: <tt class=
              "LITERAL">http://config.privoxy.org/user-manual/</tt> (or the
              shortcut: <tt class=
              "LITERAL">http://p.p/user-manual/</tt>).</p>

              <p>If the documentation is not on the local system, it can be
              accessed from a remote server, as:</p>

              <table class="c4" border="0" width="90%">
                <tr>
                  <td>
                    <pre class="SCREEN">
  user-manual  http://example.com/privoxy/user-manual/
</pre>
                  </td>
                </tr>
              </table>

              <div class="WARNING">
                <table class="WARNING" border="1" width="90%">
                  <tr>
                    <td class="c5" align="center">Warning</td>
                  </tr>

                  <tr>
                    <td align="left">
                      <p>If set, this option should be <span class=
                      "emphasis EMPHASIS c2">the first option in the config
                      file</span>, because it is used while the config file
                      is being read on start-up.</p>
                    </td>
                  </tr>
                </table>
              </div>
            </dd>
          </dl>
        </div>
      </div>

      <div class="SECT3">
        <h4 class="SECT3"><a name="TRUST-INFO-URL" id="TRUST-INFO-URL">7.1.2.
        trust-info-url</a></h4>

        <div class="VARIABLELIST">
          <dl>
            <dt>Specifies:</dt>

            <dd>
              <p>A URL to be displayed in the error page that users will see
              if access to an untrusted page is denied.</p>
            </dd>

            <dt>Type of value:</dt>

            <dd>
              <p>URL</p>
            </dd>

            <dt>Default value:</dt>

            <dd>
              <p><span class="emphasis EMPHASIS c2">Unset</span></p>
            </dd>

            <dt>Effect if unset:</dt>

            <dd>
              <p>No links are displayed on the "untrusted" error page.</p>
            </dd>

            <dt>Notes:</dt>

            <dd>
              <p>The value of this option only matters if the experimental
              trust mechanism has been activated. (See <a href=
              "config.html#TRUSTFILE"><span class=
              "emphasis EMPHASIS c2">trustfile</span></a> below.)</p>

              <p>If you use the trust mechanism, it is a good idea to write
              up some on-line documentation about your trust policy and to
              specify the URL(s) here. Use multiple times for multiple
              URLs.</p>

              <p>The URL(s) should be added to the trustfile as well, so
              users don't end up locked out from the information on why they
              were locked out in the first place!</p>
            </dd>
          </dl>
        </div>
      </div>

      <div class="SECT3">
        <h4 class="SECT3"><a name="ADMIN-ADDRESS" id="ADMIN-ADDRESS">7.1.3.
        admin-address</a></h4>

        <div class="VARIABLELIST">
          <dl>
            <dt>Specifies:</dt>

            <dd>
              <p>An email address to reach the <span class=
              "APPLICATION">Privoxy</span> administrator.</p>
            </dd>

            <dt>Type of value:</dt>

            <dd>
              <p>Email address</p>
            </dd>

            <dt>Default value:</dt>

            <dd>
              <p><span class="emphasis EMPHASIS c2">Unset</span></p>
            </dd>

            <dt>Effect if unset:</dt>

            <dd>
              <p>No email address is displayed on error pages and the CGI
              user interface.</p>
            </dd>

            <dt>Notes:</dt>

            <dd>
              <p>If both <tt class="LITERAL">admin-address</tt> and
              <tt class="LITERAL">proxy-info-url</tt> are unset, the whole
              "Local Privoxy Support" box on all generated pages will not be
              shown.</p>
            </dd>
          </dl>
        </div>
      </div>

      <div class="SECT3">
        <h4 class="SECT3"><a name="PROXY-INFO-URL" id="PROXY-INFO-URL">7.1.4.
        proxy-info-url</a></h4>

        <div class="VARIABLELIST">
          <dl>
            <dt>Specifies:</dt>

            <dd>
              <p>A URL to documentation about the local <span class=
              "APPLICATION">Privoxy</span> setup, configuration or
              policies.</p>
            </dd>

            <dt>Type of value:</dt>

            <dd>
              <p>URL</p>
            </dd>

            <dt>Default value:</dt>

            <dd>
              <p><span class="emphasis EMPHASIS c2">Unset</span></p>
            </dd>

            <dt>Effect if unset:</dt>

            <dd>
              <p>No link to local documentation is displayed on error pages
              and the CGI user interface.</p>
            </dd>

            <dt>Notes:</dt>

            <dd>
              <p>If both <tt class="LITERAL">admin-address</tt> and
              <tt class="LITERAL">proxy-info-url</tt> are unset, the whole
              "Local Privoxy Support" box on all generated pages will not be
              shown.</p>

              <p>This URL shouldn't be blocked ;-)</p>
            </dd>
          </dl>
        </div>
      </div>
    </div>

    <div class="SECT2">
      <h2 class="SECT2"><a name="CONF-LOG-LOC" id="CONF-LOG-LOC">7.2.
      Configuration and Log File Locations</a></h2>

      <p><span class="APPLICATION">Privoxy</span> can (and normally does) use
      a number of other files for additional configuration, help and logging.
      This section of the configuration file tells <span class=
      "APPLICATION">Privoxy</span> where to find those other files.</p>

      <p>The user running <span class="APPLICATION">Privoxy</span>, must have
      read permission for all configuration files, and write permission to
      any files that would be modified, such as log files and actions
      files.</p>

      <div class="SECT3">
        <h4 class="SECT3"><a name="CONFDIR" id="CONFDIR">7.2.1.
        confdir</a></h4>

        <div class="VARIABLELIST">
          <dl>
            <dt>Specifies:</dt>

            <dd>
              <p>The directory where the other configuration files are
              located.</p>
            </dd>

            <dt>Type of value:</dt>

            <dd>
              <p>Path name</p>
            </dd>

            <dt>Default value:</dt>

            <dd>
              <p>/etc/privoxy (Unix) <span class=
              "emphasis EMPHASIS c2">or</span> <span class=
              "APPLICATION">Privoxy</span> installation dir (Windows)</p>
            </dd>

            <dt>Effect if unset:</dt>

            <dd>
              <p><span class="emphasis EMPHASIS c2">Mandatory</span></p>
            </dd>

            <dt>Notes:</dt>

            <dd>
              <p>No trailing <span class="QUOTE">"<tt class=
              "LITERAL">/</tt>"</span>, please.</p>
            </dd>
          </dl>
        </div>
      </div>

      <div class="SECT3">
        <h4 class="SECT3"><a name="TEMPLDIR" id="TEMPLDIR">7.2.2.
        templdir</a></h4>

        <div class="VARIABLELIST">
          <dl>
            <dt>Specifies:</dt>

            <dd>
              <p>An alternative directory where the templates are loaded
              from.</p>
            </dd>

            <dt>Type of value:</dt>

            <dd>
              <p>Path name</p>
            </dd>

            <dt>Default value:</dt>

            <dd>
              <p>unset</p>
            </dd>

            <dt>Effect if unset:</dt>

            <dd>
              <p>The templates are assumed to be located in
              confdir/template.</p>
            </dd>

            <dt>Notes:</dt>

            <dd>
              <p><span class="APPLICATION">Privoxy's</span> original
              templates are usually overwritten with each update. Use this
              option to relocate customized templates that should be kept. As
              template variables might change between updates, you shouldn't
              expect templates to work with <span class=
              "APPLICATION">Privoxy</span> releases other than the one they
              were part of, though.</p>
            </dd>
          </dl>
        </div>
      </div>

      <div class="SECT3">
        <h4 class="SECT3"><a name="LOGDIR" id="LOGDIR">7.2.3. logdir</a></h4>

        <div class="VARIABLELIST">
          <dl>
            <dt>Specifies:</dt>

            <dd>
              <p>The directory where all logging takes place (i.e. where the
              <tt class="FILENAME">logfile</tt> is located).</p>
            </dd>

            <dt>Type of value:</dt>

            <dd>
              <p>Path name</p>
            </dd>

            <dt>Default value:</dt>

            <dd>
              <p>/var/log/privoxy (Unix) <span class=
              "emphasis EMPHASIS c2">or</span> <span class=
              "APPLICATION">Privoxy</span> installation dir (Windows)</p>
            </dd>

            <dt>Effect if unset:</dt>

            <dd>
              <p><span class="emphasis EMPHASIS c2">Mandatory</span></p>
            </dd>

            <dt>Notes:</dt>

            <dd>
              <p>No trailing <span class="QUOTE">"<tt class=
              "LITERAL">/</tt>"</span>, please.</p>
            </dd>
          </dl>
        </div>
      </div>

      <div class="SECT3">
        <h4 class="SECT3"><a name="ACTIONSFILE" id="ACTIONSFILE">7.2.4.
        actionsfile</a></h4><a name="DEFAULT.ACTION" id=
        "DEFAULT.ACTION"></a><a name="STANDARD.ACTION" id=
        "STANDARD.ACTION"></a><a name="USER.ACTION" id="USER.ACTION"></a>

        <div class="VARIABLELIST">
          <dl>
            <dt>Specifies:</dt>

            <dd>
              <p>The <a href="actions-file.html">actions file(s)</a> to
              use</p>
            </dd>

            <dt>Type of value:</dt>

            <dd>
              <p>Complete file name, relative to <tt class=
              "LITERAL">confdir</tt></p>
            </dd>

            <dt>Default values:</dt>

            <dd>
              <table border="0">
                <tbody>
                  <tr>
                    <td>
                      <p class="LITERALLAYOUT">
                      &nbsp;&nbsp;match-all.action&nbsp;#&nbsp;Actions&nbsp;that&nbsp;are&nbsp;applied&nbsp;to&nbsp;all&nbsp;sites&nbsp;and&nbsp;maybe&nbsp;overruled&nbsp;later&nbsp;on.</p>
                    </td>
                  </tr>

                  <tr>
                    <td>
                      <p class="LITERALLAYOUT">
                      &nbsp;&nbsp;default.action&nbsp;&nbsp;&nbsp;#&nbsp;Main&nbsp;actions&nbsp;file</p>
                    </td>
                  </tr>

                  <tr>
                    <td>
                      <p class="LITERALLAYOUT">
                      &nbsp;&nbsp;user.action&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;#&nbsp;User&nbsp;customizations</p>
                    </td>
                  </tr>
                </tbody>
              </table>
            </dd>

            <dt>Effect if unset:</dt>

            <dd>
              <p>No actions are taken at all. More or less neutral
              proxying.</p>
            </dd>

            <dt>Notes:</dt>

            <dd>
              <p>Multiple <tt class="LITERAL">actionsfile</tt> lines are
              permitted, and are in fact recommended!</p>

              <p>The default values are <tt class=
              "FILENAME">default.action</tt>, which is the <span class=
              "QUOTE">"main"</span> actions file maintained by the
              developers, and <tt class="FILENAME">user.action</tt>, where
              you can make your personal additions.</p>

              <p>Actions files contain all the per site and per URL
              configuration for ad blocking, cookie management, privacy
              considerations, etc. There is no point in using <span class=
              "APPLICATION">Privoxy</span> without at least one actions
              file.</p>

              <p>Note that since Privoxy 3.0.7, the complete filename,
              including the <span class="QUOTE">".action"</span> extension
              has to be specified. The syntax change was necessary to be
              consistent with the other file options and to allow previously
              forbidden characters.</p>
            </dd>
          </dl>
        </div>
      </div>

      <div class="SECT3">
        <h4 class="SECT3"><a name="FILTERFILE" id="FILTERFILE">7.2.5.
        filterfile</a></h4><a name="DEFAULT.FILTER" id="DEFAULT.FILTER"></a>

        <div class="VARIABLELIST">
          <dl>
            <dt>Specifies:</dt>

            <dd>
              <p>The <a href="filter-file.html">filter file(s)</a> to use</p>
            </dd>

            <dt>Type of value:</dt>

            <dd>
              <p>File name, relative to <tt class="LITERAL">confdir</tt></p>
            </dd>

            <dt>Default value:</dt>

            <dd>
              <p>default.filter (Unix) <span class=
              "emphasis EMPHASIS c2">or</span> default.filter.txt
              (Windows)</p>
            </dd>

            <dt>Effect if unset:</dt>

            <dd>
              <p>No textual content filtering takes place, i.e. all
              <tt class="LITERAL">+<a href=
              "actions-file.html#FILTER">filter</a>{<tt class=
              "REPLACEABLE c3">name</tt>}</tt> actions in the actions files
              are turned neutral.</p>
            </dd>

            <dt>Notes:</dt>

            <dd>
              <p>Multiple <tt class="LITERAL">filterfile</tt> lines are
              permitted.</p>

              <p>The <a href="filter-file.html">filter files</a> contain
              content modification rules that use <a href=
              "appendix.html#REGEX">regular expressions</a>. These rules
              permit powerful changes on the content of Web pages, and
              optionally the headers as well, e.g., you could try to disable
              your favorite JavaScript annoyances, re-write the actual
              displayed text, or just have some fun playing buzzword bingo
              with web pages.</p>

              <p>The <tt class="LITERAL">+<a href=
              "actions-file.html#FILTER">filter</a>{<tt class=
              "REPLACEABLE c3">name</tt>}</tt> actions rely on the relevant
              filter (<tt class="REPLACEABLE c3">name</tt>) to be defined in
              a filter file!</p>

              <p>A pre-defined filter file called <tt class=
              "FILENAME">default.filter</tt> that contains a number of useful
              filters for common problems is included in the distribution.
              See the section on the <tt class="LITERAL"><a href=
              "actions-file.html#FILTER">filter</a></tt> action for a
              list.</p>

              <p>It is recommended to place any locally adapted filters into
              a separate file, such as <tt class=
              "FILENAME">user.filter</tt>.</p>
            </dd>
          </dl>
        </div>
      </div>

      <div class="SECT3">
        <h4 class="SECT3"><a name="LOGFILE" id="LOGFILE">7.2.6.
        logfile</a></h4>

        <div class="VARIABLELIST">
          <dl>
            <dt>Specifies:</dt>

            <dd>
              <p>The log file to use</p>
            </dd>

            <dt>Type of value:</dt>

            <dd>
              <p>File name, relative to <tt class="LITERAL">logdir</tt></p>
            </dd>

            <dt>Default value:</dt>

            <dd>
              <p><span class="emphasis EMPHASIS c2">Unset (commented
              out)</span>. When activated: logfile (Unix) <span class=
              "emphasis EMPHASIS c2">or</span> privoxy.log (Windows).</p>
            </dd>

            <dt>Effect if unset:</dt>

            <dd>
              <p>No logfile is written.</p>
            </dd>

            <dt>Notes:</dt>

            <dd>
              <p>The logfile is where all logging and error messages are
              written. The level of detail and number of messages are set
              with the <tt class="LITERAL">debug</tt> option (see below). The
              logfile can be useful for tracking down a problem with
              <span class="APPLICATION">Privoxy</span> (e.g., it's not
              blocking an ad you think it should block) and it can help you
              to monitor what your browser is doing.</p>

              <p>Depending on the debug options below, the logfile may be a
              privacy risk if third parties can get access to it. As most
              users will never look at it, <span class=
              "APPLICATION">Privoxy</span> 3.0.7 and later only log fatal
              errors by default.</p>

              <p>For most troubleshooting purposes, you will have to change
              that, please refer to the debugging section for details.</p>

              <p>Your logfile will grow indefinitely, and you will probably
              want to periodically remove it. On Unix systems, you can do
              this with a cron job (see <span class="QUOTE">"man
              cron"</span>). For Red Hat based Linux distributions, a
              <b class="COMMAND">logrotate</b> script has been included.</p>

              <p>Any log files must be writable by whatever user <span class=
              "APPLICATION">Privoxy</span> is being run as (on Unix, default
              user id is <span class="QUOTE">"privoxy"</span>).</p>
            </dd>
          </dl>
        </div>
      </div>

      <div class="SECT3">
        <h4 class="SECT3"><a name="TRUSTFILE" id="TRUSTFILE">7.2.7.
        trustfile</a></h4>

        <div class="VARIABLELIST">
          <dl>
            <dt>Specifies:</dt>

            <dd>
              <p>The name of the trust file to use</p>
            </dd>

            <dt>Type of value:</dt>

            <dd>
              <p>File name, relative to <tt class="LITERAL">confdir</tt></p>
            </dd>

            <dt>Default value:</dt>

            <dd>
              <p><span class="emphasis EMPHASIS c2">Unset (commented
              out)</span>. When activated: trust (Unix) <span class=
              "emphasis EMPHASIS c2">or</span> trust.txt (Windows)</p>
            </dd>

            <dt>Effect if unset:</dt>

            <dd>
              <p>The entire trust mechanism is disabled.</p>
            </dd>

            <dt>Notes:</dt>

            <dd>
              <p>The trust mechanism is an experimental feature for building
              white-lists and should be used with care. It is <span class=
              "emphasis EMPHASIS c2">NOT</span> recommended for the casual
              user.</p>

              <p>If you specify a trust file, <span class=
              "APPLICATION">Privoxy</span> will only allow access to sites
              that are specified in the trustfile. Sites can be listed in one
              of two ways:</p>

              <p>Prepending a <tt class="LITERAL">~</tt> character limits
              access to this site only (and any sub-paths within this site),
              e.g. <tt class="LITERAL">~www.example.com</tt> allows access to
              <tt class="LITERAL">~www.example.com/features/news.html</tt>,
              etc.</p>

              <p>Or, you can designate sites as <span class=
              "emphasis EMPHASIS c2">trusted referrers</span>, by prepending
              the name with a <tt class="LITERAL">+</tt> character. The
              effect is that access to untrusted sites will be granted -- but
              only if a link from this trusted referrer was used to get
              there. The link target will then be added to the <span class=
              "QUOTE">"trustfile"</span> so that future, direct accesses will
              be granted. Sites added via this mechanism do not become
              trusted referrers themselves (i.e. they are added with a
              <tt class="LITERAL">~</tt> designation). There is a limit of
              512 such entries, after which new entries will not be made.</p>

              <p>If you use the <tt class="LITERAL">+</tt> operator in the
              trust file, it may grow considerably over time.</p>

              <p>It is recommended that <span class=
              "APPLICATION">Privoxy</span> be compiled with the <tt class=
              "LITERAL">--disable-force</tt>, <tt class=
              "LITERAL">--disable-toggle</tt> and <tt class=
              "LITERAL">--disable-editor</tt> options, if this feature is to
              be used.</p>

              <p>Possible applications include limiting Internet access for
              children.</p>
            </dd>
          </dl>
        </div>
      </div>
    </div>

    <div class="SECT2">
      <h2 class="SECT2"><a name="DEBUGGING" id="DEBUGGING">7.3.
      Debugging</a></h2>

      <p>These options are mainly useful when tracing a problem. Note that
      you might also want to invoke <span class="APPLICATION">Privoxy</span>
      with the <tt class="LITERAL">--no-daemon</tt> command line option when
      debugging.</p>

      <div class="SECT3">
        <h4 class="SECT3"><a name="DEBUG" id="DEBUG">7.3.1. debug</a></h4>

        <div class="VARIABLELIST">
          <dl>
            <dt>Specifies:</dt>

            <dd>
              <p>Key values that determine what information gets logged.</p>
            </dd>

            <dt>Type of value:</dt>

            <dd>
              <p>Integer values</p>
            </dd>

            <dt>Default value:</dt>

            <dd>
              <p>0 (i.e.: only fatal errors (that cause Privoxy to exit) are
              logged)</p>
            </dd>

            <dt>Effect if unset:</dt>

            <dd>
              <p>Default value is used (see above).</p>
            </dd>

            <dt>Notes:</dt>

            <dd>
              <p>The available debug levels are:</p>

              <table class="c4" border="0" width="90%">
                <tr>
                  <td>
                    <pre class="PROGRAMLISTING">
  debug     1 # Log the destination for each request <span class=
"APPLICATION">Privoxy</span> let through. See also debug 1024.
  debug     2 # show each connection status
  debug     4 # show I/O status
  debug     8 # show header parsing
  debug    16 # log all data written to the network
  debug    32 # debug force feature
  debug    64 # debug regular expression filters
  debug   128 # debug redirects
  debug   256 # debug GIF de-animation
  debug   512 # Common Log Format
  debug  1024 # Log the destination for requests <span class=
"APPLICATION">Privoxy</span> didn't let through, and the reason why.
  debug  2048 # CGI user interface
  debug  4096 # Startup banner and warnings.
  debug  8192 # Non-fatal errors
  debug 32768 # log all data read from the network
</pre>
                  </td>
                </tr>
              </table>

              <p>To select multiple debug levels, you can either add them or
              use multiple <tt class="LITERAL">debug</tt> lines.</p>

              <p>A debug level of 1 is informative because it will show you
              each request as it happens. <span class=
              "emphasis EMPHASIS c2">1, 1024, 4096 and 8192 are
              recommended</span> so that you will notice when things go
              wrong. The other levels are probably only of interest if you
              are hunting down a specific problem. They can produce a hell of
              an output (especially 16).</p>

              <p><span class="APPLICATION">Privoxy</span> used to ship with
              the debug levels recommended above enabled by default, but due
              to privacy concerns 3.0.7 and later are configured to only log
              fatal errors.</p>

              <p>If you are used to the more verbose settings, simply enable
              the debug lines below again.</p>

              <p>If you want to use pure CLF (Common Log Format), you should
              set <span class="QUOTE">"debug 512"</span> <span class=
              "emphasis EMPHASIS c2">ONLY</span> and not enable anything
              else.</p>

              <p><span class="APPLICATION">Privoxy</span> has a hard-coded
              limit for the length of log messages. If it's reached, messages
              are logged truncated and marked with <span class="QUOTE">"...
              [too long, truncated]"</span>.</p>

              <p>Please don't file any support requests without trying to
              reproduce the problem with increased debug level first. Once
              you read the log messages, you may even be able to solve the
              problem on your own.</p>
            </dd>
          </dl>
        </div>
      </div>

      <div class="SECT3">
        <h4 class="SECT3"><a name="SINGLE-THREADED" id=
        "SINGLE-THREADED">7.3.2. single-threaded</a></h4>

        <div class="VARIABLELIST">
          <dl>
            <dt>Specifies:</dt>

            <dd>
              <p>Whether to run only one server thread.</p>
            </dd>

            <dt>Type of value:</dt>

            <dd>
              <p><span class="emphasis EMPHASIS c2">None</span></p>
            </dd>

            <dt>Default value:</dt>

            <dd>
              <p><span class="emphasis EMPHASIS c2">Unset</span></p>
            </dd>

            <dt>Effect if unset:</dt>

            <dd>
              <p>Multi-threaded (or, where unavailable: forked) operation,
              i.e. the ability to serve multiple requests simultaneously.</p>
            </dd>

            <dt>Notes:</dt>

            <dd>
              <p>This option is only there for debugging purposes.
              <span class="emphasis EMPHASIS c2">It will drastically reduce
              performance.</span></p>
            </dd>
          </dl>
        </div>
      </div>

      <div class="SECT3">
        <h4 class="SECT3"><a name="HOSTNAME" id="HOSTNAME">7.3.3.
        hostname</a></h4>

        <div class="VARIABLELIST">
          <dl>
            <dt>Specifies:</dt>

            <dd>
              <p>The hostname shown on the CGI pages.</p>
            </dd>

            <dt>Type of value:</dt>

            <dd>
              <p>Text</p>
            </dd>

            <dt>Default value:</dt>

            <dd>
              <p><span class="emphasis EMPHASIS c2">Unset</span></p>
            </dd>

            <dt>Effect if unset:</dt>

            <dd>
              <p>The hostname provided by the operating system is used.</p>
            </dd>

            <dt>Notes:</dt>

            <dd>
              <p>On some misconfigured systems resolving the hostname fails
              or takes too much time and slows Privoxy down. Setting a fixed
              hostname works around the problem.</p>

              <p>In other circumstances it might be desirable to show a
              hostname other than the one returned by the operating system.
              For example if the system has several different hostnames and
              you don't want to use the first one.</p>

              <p>Note that Privoxy does not validate the specified hostname
              value.</p>
            </dd>
          </dl>
        </div>
      </div>
    </div>

    <div class="SECT2">
      <h2 class="SECT2"><a name="ACCESS-CONTROL" id="ACCESS-CONTROL">7.4.
      Access Control and Security</a></h2>

      <p>This section of the config file controls the security-relevant
      aspects of <span class="APPLICATION">Privoxy</span>'s
      configuration.</p>

      <div class="SECT3">
        <h4 class="SECT3"><a name="LISTEN-ADDRESS" id="LISTEN-ADDRESS">7.4.1.
        listen-address</a></h4>

        <div class="VARIABLELIST">
          <dl>
            <dt>Specifies:</dt>

            <dd>
              <p>The address and TCP port on which <span class=
              "APPLICATION">Privoxy</span> will listen for client
              requests.</p>
            </dd>

            <dt>Type of value:</dt>

            <dd>
              <p>[<tt class="REPLACEABLE c3">IP-Address</tt>]:<tt class=
              "REPLACEABLE c3">Port</tt></p>

              <p>[<tt class="REPLACEABLE c3">Hostname</tt>]:<tt class=
              "REPLACEABLE c3">Port</tt></p>
            </dd>

            <dt>Default value:</dt>

            <dd>
              <p>127.0.0.1:8118</p>
            </dd>

            <dt>Effect if unset:</dt>

            <dd>
              <p>Bind to 127.0.0.1 (IPv4 localhost), port 8118. This is
              suitable and recommended for home users who run <span class=
              "APPLICATION">Privoxy</span> on the same machine as their
              browser.</p>
            </dd>

            <dt>Notes:</dt>

            <dd>
              <p>You will need to configure your browser(s) to this proxy
              address and port.</p>

              <p>If you already have another service running on port 8118, or
              if you want to serve requests from other machines (e.g. on your
              local network) as well, you will need to override the
              default.</p>

              <p>You can use this statement multiple times to make
              <span class="APPLICATION">Privoxy</span> listen on more ports
              or more <abbr class="ABBREV">IP</abbr> addresses. Suitable if
              your operating system does not support sharing <abbr class=
              "ABBREV">IPv6</abbr> and <abbr class="ABBREV">IPv4</abbr>
              protocols on the same socket.</p>

              <p>If a hostname is used instead of an IP address, <span class=
              "APPLICATION">Privoxy</span> will try to resolve it to an IP
              address and if there are multiple, use the first one
              returned.</p>

              <p>If the address for the hostname isn't already known on the
              system (for example because it's in /etc/hostname), this may
              result in DNS traffic.</p>

              <p>If the specified address isn't available on the system, or
              if the hostname can't be resolved, <span class=
              "APPLICATION">Privoxy</span> will fail to start.</p>

              <p>IPv6 addresses containing colons have to be quoted by
              brackets. They can only be used if <span class=
              "APPLICATION">Privoxy</span> has been compiled with IPv6
              support. If you aren't sure if your version supports it, have a
              look at <tt class=
              "LITERAL">http://config.privoxy.org/show-status</tt>.</p>

              <p>Some operating systems will prefer IPv6 to IPv4 addresses
              even if the system has no IPv6 connectivity which is usually
              not expected by the user. Some even rely on DNS to resolve
              localhost which mean the "localhost" address used may not
              actually be local.</p>

              <p>It is therefore recommended to explicitly configure the
              intended IP address instead of relying on the operating system,
              unless there's a strong reason not to.</p>

              <p>If you leave out the address, <span class=
              "APPLICATION">Privoxy</span> will bind to all IPv4 interfaces
              (addresses) on your machine and may become reachable from the
              Internet and/or the local network. Be aware that some GNU/Linux
              distributions modify that behaviour without updating the
              documentation. Check for non-standard patches if your
              <span class="APPLICATION">Privoxy</span>version behaves
              differently.</p>

              <p>If you configure <span class="APPLICATION">Privoxy</span>to
              be reachable from the network, consider using <a href=
              "config.html#ACLS">access control lists</a> (ACL's, see below),
              and/or a firewall.</p>

              <p>If you open <span class="APPLICATION">Privoxy</span> to
              untrusted users, you will also want to make sure that the
              following actions are disabled: <tt class="LITERAL"><a href=
              "config.html#ENABLE-EDIT-ACTIONS">enable-edit-actions</a></tt>
              and <tt class="LITERAL"><a href=
              "config.html#ENABLE-REMOTE-TOGGLE">enable-remote-toggle</a></tt></p>

              <p>With the exception noted above, listening on multiple
              addresses is currently not supported by <span class=
              "APPLICATION">Privoxy</span> directly. It can be done on most
              operating systems by letting a packet filter redirect request
              for certain addresses to Privoxy, though.</p>
            </dd>

            <dt>Example:</dt>

            <dd>
              <p>Suppose you are running <span class=
              "APPLICATION">Privoxy</span> on a machine which has the address
              192.168.0.1 on your local private network (192.168.0.0) and has
              another outside connection with a different address. You want
              it to serve requests from inside only:</p>

              <table class="c4" border="0" width="90%">
                <tr>
                  <td>
                    <pre class="PROGRAMLISTING">
  listen-address  192.168.0.1:8118
</pre>
                  </td>
                </tr>
              </table>

              <p>Suppose you are running <span class=
              "APPLICATION">Privoxy</span> on an IPv6-capable machine and you
              want it to listen on the IPv6 address of the loopback
              device:</p>

              <table class="c4" border="0" width="90%">
                <tr>
                  <td>
                    <pre class="PROGRAMLISTING">
  listen-address [::1]:8118
</pre>
                  </td>
                </tr>
              </table>
            </dd>
          </dl>
        </div>
      </div>

      <div class="SECT3">
        <h4 class="SECT3"><a name="TOGGLE" id="TOGGLE">7.4.2. toggle</a></h4>

        <div class="VARIABLELIST">
          <dl>
            <dt>Specifies:</dt>

            <dd>
              <p>Initial state of "toggle" status</p>
            </dd>

            <dt>Type of value:</dt>

            <dd>
              <p>1 or 0</p>
            </dd>

            <dt>Default value:</dt>

            <dd>
              <p>1</p>
            </dd>

            <dt>Effect if unset:</dt>

            <dd>
              <p>Act as if toggled on</p>
            </dd>

            <dt>Notes:</dt>

            <dd>
              <p>If set to 0, <span class="APPLICATION">Privoxy</span> will
              start in <span class="QUOTE">"toggled off"</span> mode, i.e.
              mostly behave like a normal, content-neutral proxy with both ad
              blocking and content filtering disabled. See <tt class=
              "LITERAL">enable-remote-toggle</tt> below.</p>

              <p>The windows version will only display the toggle icon in the
              system tray if this option is present.</p>
            </dd>
          </dl>
        </div>
      </div>

      <div class="SECT3">
        <h4 class="SECT3"><a name="ENABLE-REMOTE-TOGGLE" id=
        "ENABLE-REMOTE-TOGGLE">7.4.3. enable-remote-toggle</a></h4>

        <div class="VARIABLELIST">
          <dl>
            <dt>Specifies:</dt>

            <dd>
              <p>Whether or not the <a href=
              "http://config.privoxy.org/toggle" target="_top">web-based
              toggle feature</a> may be used</p>
            </dd>

            <dt>Type of value:</dt>

            <dd>
              <p>0 or 1</p>
            </dd>

            <dt>Default value:</dt>

            <dd>
              <p>0</p>
            </dd>

            <dt>Effect if unset:</dt>

            <dd>
              <p>The web-based toggle feature is disabled.</p>
            </dd>

            <dt>Notes:</dt>

            <dd>
              <p>When toggled off, <span class="APPLICATION">Privoxy</span>
              mostly acts like a normal, content-neutral proxy, i.e. doesn't
              block ads or filter content.</p>

              <p>Access to the toggle feature can <span class=
              "emphasis EMPHASIS c2">not</span> be controlled separately by
              <span class="QUOTE">"ACLs"</span> or HTTP authentication, so
              that everybody who can access <span class=
              "APPLICATION">Privoxy</span> (see <span class=
              "QUOTE">"ACLs"</span> and <tt class=
              "LITERAL">listen-address</tt> above) can toggle it for all
              users. So this option is <span class="emphasis EMPHASIS c2">not
              recommended</span> for multi-user environments with untrusted
              users.</p>

              <p>Note that malicious client side code (e.g Java) is also
              capable of using this option.</p>

              <p>As a lot of <span class="APPLICATION">Privoxy</span> users
              don't read documentation, this feature is disabled by
              default.</p>

              <p>Note that you must have compiled <span class=
              "APPLICATION">Privoxy</span> with support for this feature,
              otherwise this option has no effect.</p>
            </dd>
          </dl>
        </div>
      </div>

      <div class="SECT3">
        <h4 class="SECT3"><a name="ENABLE-REMOTE-HTTP-TOGGLE" id=
        "ENABLE-REMOTE-HTTP-TOGGLE">7.4.4. enable-remote-http-toggle</a></h4>

        <div class="VARIABLELIST">
          <dl>
            <dt>Specifies:</dt>

            <dd>
              <p>Whether or not Privoxy recognizes special HTTP headers to
              change its behaviour.</p>
            </dd>

            <dt>Type of value:</dt>

            <dd>
              <p>0 or 1</p>
            </dd>

            <dt>Default value:</dt>

            <dd>
              <p>0</p>
            </dd>

            <dt>Effect if unset:</dt>

            <dd>
              <p>Privoxy ignores special HTTP headers.</p>
            </dd>

            <dt>Notes:</dt>

            <dd>
              <p>When toggled on, the client can change <span class=
              "APPLICATION">Privoxy's</span> behaviour by setting special
              HTTP headers. Currently the only supported special header is
              <span class="QUOTE">"X-Filter: No"</span>, to disable filtering
              for the ongoing request, even if it is enabled in one of the
              action files.</p>

              <p>This feature is disabled by default. If you are using
              <span class="APPLICATION">Privoxy</span> in a environment with
              trusted clients, you may enable this feature at your
              discretion. Note that malicious client side code (e.g Java) is
              also capable of using this feature.</p>

              <p>This option will be removed in future releases as it has
              been obsoleted by the more general header taggers.</p>
            </dd>
          </dl>
        </div>
      </div>

      <div class="SECT3">
        <h4 class="SECT3"><a name="ENABLE-EDIT-ACTIONS" id=
        "ENABLE-EDIT-ACTIONS">7.4.5. enable-edit-actions</a></h4>

        <div class="VARIABLELIST">
          <dl>
            <dt>Specifies:</dt>

            <dd>
              <p>Whether or not the <a href=
              "http://config.privoxy.org/show-status" target="_top">web-based
              actions file editor</a> may be used</p>
            </dd>

            <dt>Type of value:</dt>

            <dd>
              <p>0 or 1</p>
            </dd>

            <dt>Default value:</dt>

            <dd>
              <p>0</p>
            </dd>

            <dt>Effect if unset:</dt>

            <dd>
              <p>The web-based actions file editor is disabled.</p>
            </dd>

            <dt>Notes:</dt>

            <dd>
              <p>Access to the editor can <span class=
              "emphasis EMPHASIS c2">not</span> be controlled separately by
              <span class="QUOTE">"ACLs"</span> or HTTP authentication, so
              that everybody who can access <span class=
              "APPLICATION">Privoxy</span> (see <span class=
              "QUOTE">"ACLs"</span> and <tt class=
              "LITERAL">listen-address</tt> above) can modify its
              configuration for all users.</p>

              <p>This option is <span class="emphasis EMPHASIS c2">not
              recommended</span> for environments with untrusted users and as
              a lot of <span class="APPLICATION">Privoxy</span> users don't
              read documentation, this feature is disabled by default.</p>

              <p>Note that malicious client side code (e.g Java) is also
              capable of using the actions editor and you shouldn't enable
              this options unless you understand the consequences and are
              sure your browser is configured correctly.</p>

              <p>Note that you must have compiled <span class=
              "APPLICATION">Privoxy</span> with support for this feature,
              otherwise this option has no effect.</p>
            </dd>
          </dl>
        </div>
      </div>

      <div class="SECT3">
        <h4 class="SECT3"><a name="ENFORCE-BLOCKS" id="ENFORCE-BLOCKS">7.4.6.
        enforce-blocks</a></h4>

        <div class="VARIABLELIST">
          <dl>
            <dt>Specifies:</dt>

            <dd>
              <p>Whether the user is allowed to ignore blocks and can
              <span class="QUOTE">"go there anyway"</span>.</p>
            </dd>

            <dt>Type of value:</dt>

            <dd>
              <p><tt class="REPLACEABLE c3">0 or 1</tt></p>
            </dd>

            <dt>Default value:</dt>

            <dd>
              <p><span class="emphasis EMPHASIS c2">0</span></p>
            </dd>

            <dt>Effect if unset:</dt>

            <dd>
              <p>Blocks are not enforced.</p>
            </dd>

            <dt>Notes:</dt>

            <dd>
              <p><span class="APPLICATION">Privoxy</span> is mainly used to
              block and filter requests as a service to the user, for example
              to block ads and other junk that clogs the pipes. <span class=
              "APPLICATION">Privoxy's</span> configuration isn't perfect and
              sometimes innocent pages are blocked. In this situation it
              makes sense to allow the user to enforce the request and have
              <span class="APPLICATION">Privoxy</span> ignore the block.</p>

              <p>In the default configuration <span class=
              "APPLICATION">Privoxy's</span> <span class=
              "QUOTE">"Blocked"</span> page contains a <span class=
              "QUOTE">"go there anyway"</span> link to adds a special string
              (the force prefix) to the request URL. If that link is used,
              <span class="APPLICATION">Privoxy</span> will detect the force
              prefix, remove it again and let the request pass.</p>

              <p>Of course <span class="APPLICATION">Privoxy</span> can also
              be used to enforce a network policy. In that case the user
              obviously should not be able to bypass any blocks, and that's
              what the <span class="QUOTE">"enforce-blocks"</span> option is
              for. If it's enabled, <span class="APPLICATION">Privoxy</span>
              hides the <span class="QUOTE">"go there anyway"</span> link. If
              the user adds the force prefix by hand, it will not be accepted
              and the circumvention attempt is logged.</p>
            </dd>

            <dt>Examples:</dt>

            <dd>
              <p>enforce-blocks 1</p>
            </dd>
          </dl>
        </div>
      </div>

      <div class="SECT3">
        <h4 class="SECT3"><a name="ACLS" id="ACLS">7.4.7. ACLs: permit-access
        and deny-access</a></h4><a name="PERMIT-ACCESS" id=
        "PERMIT-ACCESS"></a><a name="DENY-ACCESS" id="DENY-ACCESS"></a>

        <div class="VARIABLELIST">
          <dl>
            <dt>Specifies:</dt>

            <dd>
              <p>Who can access what.</p>
            </dd>

            <dt>Type of value:</dt>

            <dd>
              <p><tt class="REPLACEABLE c3">src_addr</tt>[:<tt class=
              "REPLACEABLE c3">port</tt>][/<tt class=
              "REPLACEABLE c3">src_masklen</tt>] [<tt class=
              "REPLACEABLE c3">dst_addr</tt>[:<tt class=
              "REPLACEABLE c3">port</tt>][/<tt class=
              "REPLACEABLE c3">dst_masklen</tt>]]</p>

              <p>Where <tt class="REPLACEABLE c3">src_addr</tt> and
              <tt class="REPLACEABLE c3">dst_addr</tt> are IPv4 addresses in
              dotted decimal notation or valid DNS names, <tt class=
              "REPLACEABLE c3">port</tt> is a port number, and <tt class=
              "REPLACEABLE c3">src_masklen</tt> and <tt class=
              "REPLACEABLE c3">dst_masklen</tt> are subnet masks in CIDR
              notation, i.e. integer values from 2 to 30 representing the
              length (in bits) of the network address. The masks and the
              whole destination part are optional.</p>

              <p>If your system implements <a href=
              "http://tools.ietf.org/html/rfc3493" target="_top">RFC
              3493</a>, then <tt class="REPLACEABLE c3">src_addr</tt> and
              <tt class="REPLACEABLE c3">dst_addr</tt> can be IPv6 addresses
              delimeted by brackets, <tt class="REPLACEABLE c3">port</tt> can
              be a number or a service name, and <tt class=
              "REPLACEABLE c3">src_masklen</tt> and <tt class=
              "REPLACEABLE c3">dst_masklen</tt> can be a number from 0 to
              128.</p>
            </dd>

            <dt>Default value:</dt>

            <dd>
              <p><span class="emphasis EMPHASIS c2">Unset</span></p>

              <p>If no <tt class="REPLACEABLE c3">port</tt> is specified, any
              port will match. If no <tt class=
              "REPLACEABLE c3">src_masklen</tt> or <tt class=
              "REPLACEABLE c3">src_masklen</tt> is given, the complete IP
              address has to match (i.e. 32 bits for IPv4 and 128 bits for
              IPv6).</p>
            </dd>

            <dt>Effect if unset:</dt>

            <dd>
              <p>Don't restrict access further than implied by <tt class=
              "LITERAL">listen-address</tt></p>
            </dd>

            <dt>Notes:</dt>

            <dd>
              <p>Access controls are included at the request of ISPs and
              systems administrators, and <span class=
              "emphasis EMPHASIS c2">are not usually needed by individual
              users</span>. For a typical home user, it will normally suffice
              to ensure that <span class="APPLICATION">Privoxy</span> only
              listens on the localhost (127.0.0.1) or internal (home) network
              address by means of the <a href=
              "config.html#LISTEN-ADDRESS"><span class=
              "emphasis EMPHASIS c2">listen-address</span></a> option.</p>

              <p>Please see the warnings in the FAQ that <span class=
              "APPLICATION">Privoxy</span> is not intended to be a substitute
              for a firewall or to encourage anyone to defer addressing basic
              security weaknesses.</p>

              <p>Multiple ACL lines are OK. If any ACLs are specified,
              <span class="APPLICATION">Privoxy</span> only talks to IP
              addresses that match at least one <tt class=
              "LITERAL">permit-access</tt> line and don't match any
              subsequent <tt class="LITERAL">deny-access</tt> line. In other
              words, the last match wins, with the default being <tt class=
              "LITERAL">deny-access</tt>.</p>

              <p>If <span class="APPLICATION">Privoxy</span> is using a
              forwarder (see <tt class="LITERAL">forward</tt> below) for a
              particular destination URL, the <tt class=
              "REPLACEABLE c3">dst_addr</tt> that is examined is the address
              of the forwarder and <span class=
              "emphasis EMPHASIS c2">NOT</span> the address of the ultimate
              target. This is necessary because it may be impossible for the
              local <span class="APPLICATION">Privoxy</span> to determine the
              IP address of the ultimate target (that's often what gateways
              are used for).</p>

              <p>You should prefer using IP addresses over DNS names, because
              the address lookups take time. All DNS names must resolve! You
              can <span class="emphasis EMPHASIS c2">not</span> use domain
              patterns like <span class="QUOTE">"*.org"</span> or partial
              domain names. If a DNS name resolves to multiple IP addresses,
              only the first one is used.</p>

              <p>Some systems allow IPv4 clients to connect to IPv6 server
              sockets. Then the client's IPv4 address will be translated by
              the system into IPv6 address space with special prefix
              ::ffff:0:0/96 (so called IPv4 mapped IPv6 address).
              <span class="APPLICATION">Privoxy</span> can handle it and maps
              such ACL addresses automatically.</p>

              <p>Denying access to particular sites by ACL may have undesired
              side effects if the site in question is hosted on a machine
              which also hosts other sites (most sites are).</p>
            </dd>

            <dt>Examples:</dt>

            <dd>
              <p>Explicitly define the default behavior if no ACL and
              <tt class="LITERAL">listen-address</tt> are set: <span class=
              "QUOTE">"localhost"</span> is OK. The absence of a <tt class=
              "REPLACEABLE c3">dst_addr</tt> implies that <span class=
              "emphasis EMPHASIS c2">all</span> destination addresses are
              OK:</p>

              <table class="c4" border="0" width="90%">
                <tr>
                  <td>
                    <pre class="SCREEN">
  permit-access  localhost
</pre>
                  </td>
                </tr>
              </table>

              <p>Allow any host on the same class C subnet as www.privoxy.org
              access to nothing but www.example.com (or other domains hosted
              on the same system):</p>

              <table class="c4" border="0" width="90%">
                <tr>
                  <td>
                    <pre class="SCREEN">
  permit-access  www.privoxy.org/24 www.example.com/32
</pre>
                  </td>
                </tr>
              </table>

              <p>Allow access from any host on the 26-bit subnet
              192.168.45.64 to anywhere, with the exception that
              192.168.45.73 may not access the IP address behind
              www.dirty-stuff.example.com:</p>

              <table class="c4" border="0" width="90%">
                <tr>
                  <td>
                    <pre class="SCREEN">
  permit-access  192.168.45.64/26
  deny-access    192.168.45.73    www.dirty-stuff.example.com
</pre>
                  </td>
                </tr>
              </table>

              <p>Allow access from the IPv4 network 192.0.2.0/24 even if
              listening on an IPv6 wild card address (not supported on all
              platforms):</p>

              <table class="c4" border="0" width="90%">
                <tr>
                  <td>
                    <pre class="PROGRAMLISTING">
  permit-access  192.0.2.0/24
</pre>
                  </td>
                </tr>
              </table>

              <p>This is equivalent to the following line even if listening
              on an IPv4 address (not supported on all platforms):</p>

              <table class="c4" border="0" width="90%">
                <tr>
                  <td>
                    <pre class="PROGRAMLISTING">
  permit-access  [::ffff:192.0.2.0]/120
</pre>
                  </td>
                </tr>
              </table>
            </dd>
          </dl>
        </div>
      </div>

      <div class="SECT3">
        <h4 class="SECT3"><a name="BUFFER-LIMIT" id="BUFFER-LIMIT">7.4.8.
        buffer-limit</a></h4>

        <div class="VARIABLELIST">
          <dl>
            <dt>Specifies:</dt>

            <dd>
              <p>Maximum size of the buffer for content filtering.</p>
            </dd>

            <dt>Type of value:</dt>

            <dd>
              <p>Size in Kbytes</p>
            </dd>

            <dt>Default value:</dt>

            <dd>
              <p>4096</p>
            </dd>

            <dt>Effect if unset:</dt>

            <dd>
              <p>Use a 4MB (4096 KB) limit.</p>
            </dd>

            <dt>Notes:</dt>

            <dd>
              <p>For content filtering, i.e. the <tt class=
              "LITERAL">+filter</tt> and <tt class=
              "LITERAL">+deanimate-gif</tt> actions, it is necessary that
              <span class="APPLICATION">Privoxy</span> buffers the entire
              document body. This can be potentially dangerous, since a
              server could just keep sending data indefinitely and wait for
              your RAM to exhaust -- with nasty consequences. Hence this
              option.</p>

              <p>When a document buffer size reaches the <tt class=
              "LITERAL">buffer-limit</tt>, it is flushed to the client
              unfiltered and no further attempt to filter the rest of the
              document is made. Remember that there may be multiple threads
              running, which might require up to <tt class=
              "LITERAL">buffer-limit</tt> Kbytes <span class=
              "emphasis EMPHASIS c2">each</span>, unless you have enabled
              <span class="QUOTE">"single-threaded"</span> above.</p>
            </dd>
          </dl>
        </div>
      </div>
    </div>

    <div class="SECT2">
      <h2 class="SECT2"><a name="FORWARDING" id="FORWARDING">7.5.
      Forwarding</a></h2>

      <p>This feature allows routing of HTTP requests through a chain of
      multiple proxies.</p>

      <p>Forwarding can be used to chain Privoxy with a caching proxy to
      speed up browsing. Using a parent proxy may also be necessary if the
      machine that <span class="APPLICATION">Privoxy</span> runs on has no
      direct Internet access.</p>

      <p>Note that parent proxies can severely decrease your privacy level.
      For example a parent proxy could add your IP address to the request
      headers and if it's a caching proxy it may add the <span class=
      "QUOTE">"Etag"</span> header to revalidation requests again, even
      though you configured Privoxy to remove it. It may also ignore
      Privoxy's header time randomization and use the original values which
      could be used by the server as cookie replacement to track your steps
      between visits.</p>

      <p>Also specified here are SOCKS proxies. <span class=
      "APPLICATION">Privoxy</span> supports the SOCKS 4 and SOCKS 4A
      protocols.</p>

      <div class="SECT3">
        <h4 class="SECT3"><a name="FORWARD" id="FORWARD">7.5.1.
        forward</a></h4>

        <div class="VARIABLELIST">
          <dl>
            <dt>Specifies:</dt>

            <dd>
              <p>To which parent HTTP proxy specific requests should be
              routed.</p>
            </dd>

            <dt>Type of value:</dt>

            <dd>
              <p><tt class="REPLACEABLE c3">target_pattern</tt> <tt class=
              "REPLACEABLE c3">http_parent</tt>[:<tt class=
              "REPLACEABLE c3">port</tt>]</p>

              <p>where <tt class="REPLACEABLE c3">target_pattern</tt> is a
              <a href="actions-file.html#AF-PATTERNS">URL pattern</a> that
              specifies to which requests (i.e. URLs) this forward rule shall
              apply. Use <tt class="LITERAL">/</tt> to denote <span class=
              "QUOTE">"all URLs"</span>. <tt class=
              "REPLACEABLE c3">http_parent</tt>[:<tt class=
              "REPLACEABLE c3">port</tt>] is the DNS name or IP address of
              the parent HTTP proxy through which the requests should be
              forwarded, optionally followed by its listening port (default:
              8000). Use a single dot (<tt class="LITERAL">.</tt>) to denote
              <span class="QUOTE">"no forwarding"</span>.</p>
            </dd>

            <dt>Default value:</dt>

            <dd>
              <p><span class="emphasis EMPHASIS c2">Unset</span></p>
            </dd>

            <dt>Effect if unset:</dt>

            <dd>
              <p>Don't use parent HTTP proxies.</p>
            </dd>

            <dt>Notes:</dt>

            <dd>
              <p>If <tt class="REPLACEABLE c3">http_parent</tt> is
              <span class="QUOTE">"."</span>, then requests are not forwarded
              to another HTTP proxy but are made directly to the web
              servers.</p>

              <p><tt class="REPLACEABLE c3">http_parent</tt> can be a
              numerical IPv6 address (if <a href=
              "http://tools.ietf.org/html/rfc3493" target="_top">RFC 3493</a>
              is implemented). To prevent clashes with the port delimiter,
              the whole IP address has to be put into brackets. On the other
              hand a <tt class="REPLACEABLE c3">target_pattern</tt>
              containing an IPv6 address has to be put into angle brackets
              (normal brackets are reserved for regular expressions
              already).</p>

              <p>Multiple lines are OK, they are checked in sequence, and the
              last match wins.</p>
            </dd>

            <dt>Examples:</dt>

            <dd>
              <p>Everything goes to an example parent proxy, except SSL on
              port 443 (which it doesn't handle):</p>

              <table class="c4" border="0" width="90%">
                <tr>
                  <td>
                    <pre class="SCREEN">
  forward   /      parent-proxy.example.org:8080
  forward   :443   .
</pre>
                  </td>
                </tr>
              </table>

              <p>Everything goes to our example ISP's caching proxy, except
              for requests to that ISP's sites:</p>

              <table class="c4" border="0" width="90%">
                <tr>
                  <td>
                    <pre class="SCREEN">
  forward   /                  caching-proxy.isp.example.net:8000
  forward   .isp.example.net   .
</pre>
                  </td>
                </tr>
              </table>

              <p>Parent proxy specified by an IPv6 address:</p>

              <table class="c4" border="0" width="90%">
                <tr>
                  <td>
                    <pre class="PROGRAMLISTING">
  forward   /                   [2001:DB8::1]:8000
</pre>
                  </td>
                </tr>
              </table>

              <p>Suppose your parent proxy doesn't support IPv6:</p>

              <table class="c4" border="0" width="90%">
                <tr>
                  <td>
                    <pre class="PROGRAMLISTING">
  forward  /                        parent-proxy.example.org:8000
  forward  ipv6-server.example.org  .
  forward  &lt;[2-3][0-9a-f][0-9a-f][0-9a-f]:*&gt;   .
</pre>
                  </td>
                </tr>
              </table>
            </dd>
          </dl>
        </div>
      </div>

      <div class="SECT3">
        <h4 class="SECT3"><a name="SOCKS" id="SOCKS">7.5.2. forward-socks4,
        forward-socks4a and forward-socks5</a></h4><a name="FORWARD-SOCKS4"
        id="FORWARD-SOCKS4"></a><a name="FORWARD-SOCKS4A" id=
        "FORWARD-SOCKS4A"></a>

        <div class="VARIABLELIST">
          <dl>
            <dt>Specifies:</dt>

            <dd>
              <p>Through which SOCKS proxy (and optionally to which parent
              HTTP proxy) specific requests should be routed.</p>
            </dd>

            <dt>Type of value:</dt>

            <dd>
              <p><tt class="REPLACEABLE c3">target_pattern</tt> <tt class=
              "REPLACEABLE c3">socks_proxy</tt>[:<tt class=
              "REPLACEABLE c3">port</tt>] <tt class=
              "REPLACEABLE c3">http_parent</tt>[:<tt class=
              "REPLACEABLE c3">port</tt>]</p>

              <p>where <tt class="REPLACEABLE c3">target_pattern</tt> is a
              <a href="actions-file.html#AF-PATTERNS">URL pattern</a> that
              specifies to which requests (i.e. URLs) this forward rule shall
              apply. Use <tt class="LITERAL">/</tt> to denote <span class=
              "QUOTE">"all URLs"</span>. <tt class=
              "REPLACEABLE c3">http_parent</tt> and <tt class=
              "REPLACEABLE c3">socks_proxy</tt> are IP addresses in dotted
              decimal notation or valid DNS names (<tt class=
              "REPLACEABLE c3">http_parent</tt> may be <span class=
              "QUOTE">"."</span> to denote <span class="QUOTE">"no HTTP
              forwarding"</span>), and the optional <tt class=
              "REPLACEABLE c3">port</tt> parameters are TCP ports, i.e.
              integer values from 1 to 65535</p>
            </dd>

            <dt>Default value:</dt>

            <dd>
              <p><span class="emphasis EMPHASIS c2">Unset</span></p>
            </dd>

            <dt>Effect if unset:</dt>

            <dd>
              <p>Don't use SOCKS proxies.</p>
            </dd>

            <dt>Notes:</dt>

            <dd>
              <p>Multiple lines are OK, they are checked in sequence, and the
              last match wins.</p>

              <p>The difference between <tt class=
              "LITERAL">forward-socks4</tt> and <tt class=
              "LITERAL">forward-socks4a</tt> is that in the SOCKS 4A
              protocol, the DNS resolution of the target hostname happens on
              the SOCKS server, while in SOCKS 4 it happens locally.</p>

              <p>With <tt class="LITERAL">forward-socks5</tt> the DNS
              resolution will happen on the remote server as well.</p>

              <p><tt class="REPLACEABLE c3">socks_proxy</tt> and <tt class=
              "REPLACEABLE c3">http_parent</tt> can be a numerical IPv6
              address (if <a href="http://tools.ietf.org/html/rfc3493"
              target="_top">RFC 3493</a> is implemented). To prevent clashes
              with the port delimiter, the whole IP address has to be put
              into brackets. On the other hand a <tt class=
              "REPLACEABLE c3">target_pattern</tt> containing an IPv6 address
              has to be put into angle brackets (normal brackets are reserved
              for regular expressions already).</p>

              <p>If <tt class="REPLACEABLE c3">http_parent</tt> is
              <span class="QUOTE">"."</span>, then requests are not forwarded
              to another HTTP proxy but are made (HTTP-wise) directly to the
              web servers, albeit through a SOCKS proxy.</p>
            </dd>

            <dt>Examples:</dt>

            <dd>
              <p>From the company example.com, direct connections are made to
              all <span class="QUOTE">"internal"</span> domains, but
              everything outbound goes through their ISP's proxy by way of
              example.com's corporate SOCKS 4A gateway to the Internet.</p>

              <table class="c4" border="0" width="90%">
                <tr>
                  <td>
                    <pre class="SCREEN">
  forward-socks4a   /              socks-gw.example.com:1080  www-cache.isp.example.net:8080
  forward           .example.com   .
</pre>
                  </td>
                </tr>
              </table>

              <p>A rule that uses a SOCKS 4 gateway for all destinations but
              no HTTP parent looks like this:</p>

              <table class="c4" border="0" width="90%">
                <tr>
                  <td>
                    <pre class="SCREEN">
  forward-socks4   /               socks-gw.example.com:1080  .
</pre>
                  </td>
                </tr>
              </table>

              <p>To chain Privoxy and Tor, both running on the same system,
              you would use something like:</p>

              <table class="c4" border="0" width="90%">
                <tr>
                  <td>
                    <pre class="SCREEN">
  forward-socks5   /               127.0.0.1:9050 .
</pre>
                  </td>
                </tr>
              </table>

              <p>The public <span class="APPLICATION">Tor</span> network
              can't be used to reach your local network, if you need to
              access local servers you therefore might want to make some
              exceptions:</p>

              <table class="c4" border="0" width="90%">
                <tr>
                  <td>
                    <pre class="SCREEN">
  forward         192.168.*.*/     .
  forward            10.*.*.*/     .
  forward           127.*.*.*/     .
</pre>
                  </td>
                </tr>
              </table>

              <p>Unencrypted connections to systems in these address ranges
              will be as (un)secure as the local network is, but the
              alternative is that you can't reach the local network through
              <span class="APPLICATION">Privoxy</span> at all. Of course this
              may actually be desired and there is no reason to make these
              exceptions if you aren't sure you need them.</p>

              <p>If you also want to be able to reach servers in your local
              network by using their names, you will need additional
              exceptions that look like this:</p>

              <table class="c4" border="0" width="90%">
                <tr>
                  <td>
                    <pre class="SCREEN">
 forward           localhost/     .
</pre>
                  </td>
                </tr>
              </table>
            </dd>
          </dl>
        </div>
      </div>

      <div class="SECT3">
        <h4 class="SECT3"><a name="ADVANCED-FORWARDING-EXAMPLES" id=
        "ADVANCED-FORWARDING-EXAMPLES">7.5.3. Advanced Forwarding
        Examples</a></h4>

        <p>If you have links to multiple ISPs that provide various special
        content only to their subscribers, you can configure multiple
        <span class="APPLICATION">Privoxies</span> which have connections to
        the respective ISPs to act as forwarders to each other, so that
        <span class="emphasis EMPHASIS c2">your</span> users can see the
        internal content of all ISPs.</p>

        <p>Assume that host-a has a PPP connection to isp-a.example.net. And
        host-b has a PPP connection to isp-b.example.org. Both run
        <span class="APPLICATION">Privoxy</span>. Their forwarding
        configuration can look like this:</p>

        <p>host-a:</p>

        <table class="c4" border="0" width="100%">
          <tr>
            <td>
              <pre class="SCREEN">
  forward    /           .
  forward    .isp-b.example.net  host-b:8118
</pre>
            </td>
          </tr>
        </table>

        <p>host-b:</p>

        <table class="c4" border="0" width="100%">
          <tr>
            <td>
              <pre class="SCREEN">
  forward    /           .
  forward    .isp-a.example.org  host-a:8118
</pre>
            </td>
          </tr>
        </table>

        <p>Now, your users can set their browser's proxy to use either host-a
        or host-b and be able to browse the internal content of both isp-a
        and isp-b.</p>

        <p>If you intend to chain <span class="APPLICATION">Privoxy</span>
        and <span class="APPLICATION">squid</span> locally, then chaining as
        <tt class="LITERAL">browser -&gt; squid -&gt; privoxy</tt> is the
        recommended way.</p>

        <p>Assuming that <span class="APPLICATION">Privoxy</span> and
        <span class="APPLICATION">squid</span> run on the same box, your
        <span class="APPLICATION">squid</span> configuration could then look
        like this:</p>

        <table class="c4" border="0" width="100%">
          <tr>
            <td>
              <pre class="SCREEN">
  # Define Privoxy as parent proxy (without ICP)
  cache_peer 127.0.0.1 parent 8118 7 no-query

  # Define ACL for protocol FTP
  acl ftp proto FTP

  # Do not forward FTP requests to Privoxy
  always_direct allow ftp

  # Forward all the rest to Privoxy
  never_direct allow all
</pre>
            </td>
          </tr>
        </table>

        <p>You would then need to change your browser's proxy settings to
        <span class="APPLICATION">squid</span>'s address and port. Squid
        normally uses port 3128. If unsure consult <tt class=
        "LITERAL">http_port</tt> in <tt class="FILENAME">squid.conf</tt>.</p>

        <p>You could just as well decide to only forward requests you suspect
        of leading to Windows executables through a virus-scanning parent
        proxy, say, on <tt class="LITERAL">antivir.example.com</tt>, port
        8010:</p>

        <table class="c4" border="0" width="100%">
          <tr>
            <td>
              <pre class="SCREEN">
  forward   /                          .
  forward   /.*\.(exe|com|dll|zip)$    antivir.example.com:8010
</pre>
            </td>
          </tr>
        </table>
      </div>

      <div class="SECT3">
        <h4 class="SECT3"><a name="FORWARDED-CONNECT-RETRIES" id=
        "FORWARDED-CONNECT-RETRIES">7.5.4. forwarded-connect-retries</a></h4>

        <div class="VARIABLELIST">
          <dl>
            <dt>Specifies:</dt>

            <dd>
              <p>How often Privoxy retries if a forwarded connection request
              fails.</p>
            </dd>

            <dt>Type of value:</dt>

            <dd>
              <p><tt class="REPLACEABLE c3">Number of retries.</tt></p>
            </dd>

            <dt>Default value:</dt>

            <dd>
              <p><span class="emphasis EMPHASIS c2">0</span></p>
            </dd>

            <dt>Effect if unset:</dt>

            <dd>
              <p>Connections forwarded through other proxies are treated like
              direct connections and no retry attempts are made.</p>
            </dd>

            <dt>Notes:</dt>

            <dd>
              <p><tt class="REPLACEABLE c3">forwarded-connect-retries</tt> is
              mainly interesting for socks4a connections, where <span class=
              "APPLICATION">Privoxy</span> can't detect why the connections
              failed. The connection might have failed because of a DNS
              timeout in which case a retry makes sense, but it might also
              have failed because the server doesn't exist or isn't
              reachable. In this case the retry will just delay the
              appearance of Privoxy's error message.</p>

              <p>Note that in the context of this option, <span class=
              "QUOTE">"forwarded connections"</span> includes all connections
              that Privoxy forwards through other proxies. This option is not
              limited to the HTTP CONNECT method.</p>

              <p>Only use this option, if you are getting lots of
              forwarding-related error messages that go away when you try
              again manually. Start with a small value and check Privoxy's
              logfile from time to time, to see how many retries are usually
              needed.</p>
            </dd>

            <dt>Examples:</dt>

            <dd>
              <p>forwarded-connect-retries 1</p>
            </dd>
          </dl>
        </div>
      </div>
    </div>

    <div class="SECT2">
      <h2 class="SECT2"><a name="MISC" id="MISC">7.6. Miscellaneous</a></h2>

      <div class="SECT3">
        <h4 class="SECT3"><a name="ACCEPT-INTERCEPTED-REQUESTS" id=
        "ACCEPT-INTERCEPTED-REQUESTS">7.6.1.
        accept-intercepted-requests</a></h4>

        <div class="VARIABLELIST">
          <dl>
            <dt>Specifies:</dt>

            <dd>
              <p>Whether intercepted requests should be treated as valid.</p>
            </dd>

            <dt>Type of value:</dt>

            <dd>
              <p><tt class="REPLACEABLE c3">0 or 1</tt></p>
            </dd>

            <dt>Default value:</dt>

            <dd>
              <p><span class="emphasis EMPHASIS c2">0</span></p>
            </dd>

            <dt>Effect if unset:</dt>

            <dd>
              <p>Only proxy requests are accepted, intercepted requests are
              treated as invalid.</p>
            </dd>

            <dt>Notes:</dt>

            <dd>
              <p>If you don't trust your clients and want to force them to
              use <span class="APPLICATION">Privoxy</span>, enable this
              option and configure your packet filter to redirect outgoing
              HTTP connections into <span class=
              "APPLICATION">Privoxy</span>.</p>

              <p>Make sure that <span class="APPLICATION">Privoxy's</span>
              own requests aren't redirected as well. Additionally take care
              that <span class="APPLICATION">Privoxy</span> can't
              intentionally connect to itself, otherwise you could run into
              redirection loops if <span class="APPLICATION">Privoxy's</span>
              listening port is reachable by the outside or an attacker has
              access to the pages you visit.</p>
            </dd>

            <dt>Examples:</dt>

            <dd>
              <p>accept-intercepted-requests 1</p>
            </dd>
          </dl>
        </div>
      </div>

      <div class="SECT3">
        <h4 class="SECT3"><a name="ALLOW-CGI-REQUEST-CRUNCHING" id=
        "ALLOW-CGI-REQUEST-CRUNCHING">7.6.2.
        allow-cgi-request-crunching</a></h4>

        <div class="VARIABLELIST">
          <dl>
            <dt>Specifies:</dt>

            <dd>
              <p>Whether requests to <span class=
              "APPLICATION">Privoxy's</span> CGI pages can be blocked or
              redirected.</p>
            </dd>

            <dt>Type of value:</dt>

            <dd>
              <p><tt class="REPLACEABLE c3">0 or 1</tt></p>
            </dd>

            <dt>Default value:</dt>

            <dd>
              <p><span class="emphasis EMPHASIS c2">0</span></p>
            </dd>

            <dt>Effect if unset:</dt>

            <dd>
              <p><span class="APPLICATION">Privoxy</span> ignores block and
              redirect actions for its CGI pages.</p>
            </dd>

            <dt>Notes:</dt>

            <dd>
              <p>By default <span class="APPLICATION">Privoxy</span> ignores
              block or redirect actions for its CGI pages. Intercepting these
              requests can be useful in multi-user setups to implement
              fine-grained access control, but it can also render the
              complete web interface useless and make debugging problems
              painful if done without care.</p>

              <p>Don't enable this option unless you're sure that you really
              need it.</p>
            </dd>

            <dt>Examples:</dt>

            <dd>
              <p>allow-cgi-request-crunching 1</p>
            </dd>
          </dl>
        </div>
      </div>

      <div class="SECT3">
        <h4 class="SECT3"><a name="SPLIT-LARGE-FORMS" id=
        "SPLIT-LARGE-FORMS">7.6.3. split-large-forms</a></h4>

        <div class="VARIABLELIST">
          <dl>
            <dt>Specifies:</dt>

            <dd>
              <p>Whether the CGI interface should stay compatible with broken
              HTTP clients.</p>
            </dd>

            <dt>Type of value:</dt>

            <dd>
              <p><tt class="REPLACEABLE c3">0 or 1</tt></p>
            </dd>

            <dt>Default value:</dt>

            <dd>
              <p><span class="emphasis EMPHASIS c2">0</span></p>
            </dd>

            <dt>Effect if unset:</dt>

            <dd>
              <p>The CGI form generate long GET URLs.</p>
            </dd>

            <dt>Notes:</dt>

            <dd>
              <p><span class="APPLICATION">Privoxy's</span> CGI forms can
              lead to rather long URLs. This isn't a problem as far as the
              HTTP standard is concerned, but it can confuse clients with
              arbitrary URL length limitations.</p>

              <p>Enabling split-large-forms causes <span class=
              "APPLICATION">Privoxy</span> to divide big forms into smaller
              ones to keep the URL length down. It makes editing a lot less
              convenient and you can no longer submit all changes at once,
              but at least it works around this browser bug.</p>

              <p>If you don't notice any editing problems, there is no reason
              to enable this option, but if one of the submit buttons appears
              to be broken, you should give it a try.</p>
            </dd>

            <dt>Examples:</dt>

            <dd>
              <p>split-large-forms 1</p>
            </dd>
          </dl>
        </div>
      </div>

      <div class="SECT3">
        <h4 class="SECT3"><a name="KEEP-ALIVE-TIMEOUT" id=
        "KEEP-ALIVE-TIMEOUT">7.6.4. keep-alive-timeout</a></h4>

        <div class="VARIABLELIST">
          <dl>
            <dt>Specifies:</dt>

            <dd>
              <p>Number of seconds after which an open connection will no
              longer be reused.</p>
            </dd>

            <dt>Type of value:</dt>

            <dd>
              <p><tt class="REPLACEABLE c3">Time in seconds.</tt></p>
            </dd>

            <dt>Default value:</dt>

            <dd>
              <p>None</p>
            </dd>

            <dt>Effect if unset:</dt>

            <dd>
              <p>Connections are not kept alive.</p>
            </dd>

            <dt>Notes:</dt>

            <dd>
              <p>This option allows clients to keep the connection to
              <span class="APPLICATION">Privoxy</span> alive. If the server
              supports it, <span class="APPLICATION">Privoxy</span> will keep
              the connection to the server alive as well. Under certain
              circumstances this may result in speed-ups.</p>

              <p>By default, <span class="APPLICATION">Privoxy</span> will
              close the connection to the server if the client connection
              gets closed, or if the specified timeout has been reached
              without a new request coming in. This behaviour can be changed
              with the <a href="#CONNECTION-SHARING" target=
              "_top">connection-sharing</a> option.</p>

              <p>This option has no effect if <span class=
              "APPLICATION">Privoxy</span> has been compiled without
              keep-alive support.</p>

              <p>Note that a timeout of five seconds as used in the default
              configuration file significantly decreases the number of
              connections that will be reused. The value is used because some
              browsers limit the number of connections they open to a single
              host and apply the same limit to proxies. This can result in a
              single website <span class="QUOTE">"grabbing"</span> all the
              connections the browser allows, which means connections to
              other websites can't be opened until the connections currently
              in use time out.</p>

              <p>Several users have reported this as a Privoxy bug, so the
              default value has been reduced. Consider increasing it to 300
              seconds or even more if you think your browser can handle it.
              If your browser appears to be hanging it can't.</p>
            </dd>

            <dt>Examples:</dt>

            <dd>
              <p>keep-alive-timeout 300</p>
            </dd>
          </dl>
        </div>
      </div>

      <div class="SECT3">
        <h4 class="SECT3"><a name="DEFAULT-SERVER-TIMEOUT" id=
        "DEFAULT-SERVER-TIMEOUT">7.6.5. default-server-timeout</a></h4>

        <div class="VARIABLELIST">
          <dl>
            <dt>Specifies:</dt>

            <dd>
              <p>Assumed server-side keep-alive timeout if not specified by
              the server.</p>
            </dd>

            <dt>Type of value:</dt>

            <dd>
              <p><tt class="REPLACEABLE c3">Time in seconds.</tt></p>
            </dd>

            <dt>Default value:</dt>

            <dd>
              <p>None</p>
            </dd>

            <dt>Effect if unset:</dt>

            <dd>
              <p>Connections for which the server didn't specify the
              keep-alive timeout are not reused.</p>
            </dd>

            <dt>Notes:</dt>

            <dd>
              <p>Enabling this option significantly increases the number of
              connections that are reused, provided the <a href=
              "#KEEP-ALIVE-TIMEOUT" target="_top">keep-alive-timeout</a>
              option is also enabled.</p>

              <p>While it also increases the number of connections problems
              when <span class="APPLICATION">Privoxy</span> tries to reuse a
              connection that already has been closed on the server side, or
              is closed while <span class="APPLICATION">Privoxy</span> is
              trying to reuse it, this should only be a problem if it happens
              for the first request sent by the client. If it happens for
              requests on reused client connections, <span class=
              "APPLICATION">Privoxy</span> will simply close the connection
              and the client is supposed to retry the request without
              bothering the user.</p>

              <p>Enabling this option is therefore only recommended if the
              <a href="#CONNECTION-SHARING" target=
              "_top">connection-sharing</a> option is disabled.</p>

              <p>It is an error to specify a value larger than the <a href=
              "#KEEP-ALIVE-TIMEOUT" target="_top">keep-alive-timeout</a>
              value.</p>

              <p>This option has no effect if <span class=
              "APPLICATION">Privoxy</span> has been compiled without
              keep-alive support.</p>
            </dd>

            <dt>Examples:</dt>

            <dd>
              <p>default-server-timeout 60</p>
            </dd>
          </dl>
        </div>
      </div>

      <div class="SECT3">
        <h4 class="SECT3"><a name="CONNECTION-SHARING" id=
        "CONNECTION-SHARING">7.6.6. connection-sharing</a></h4>

        <div class="VARIABLELIST">
          <dl>
            <dt>Specifies:</dt>

            <dd>
              <p>Whether or not outgoing connections that have been kept
              alive should be shared between different incoming
              connections.</p>
            </dd>

            <dt>Type of value:</dt>

            <dd>
              <p><tt class="REPLACEABLE c3">0 or 1</tt></p>
            </dd>

            <dt>Default value:</dt>

            <dd>
              <p>None</p>
            </dd>

            <dt>Effect if unset:</dt>

            <dd>
              <p>Connections are not shared.</p>
            </dd>

            <dt>Notes:</dt>

            <dd>
              <p>This option has no effect if <span class=
              "APPLICATION">Privoxy</span> has been compiled without
              keep-alive support, or if it's disabled.</p>
            </dd>

            <dt>Notes:</dt>

            <dd>
              <p>Note that reusing connections doesn't necessary cause
              speedups. There are also a few privacy implications you should
              be aware of.</p>

              <p>If this option is effective, outgoing connections are shared
              between clients (if there are more than one) and closing the
              browser that initiated the outgoing connection does no longer
              affect the connection between <span class=
              "APPLICATION">Privoxy</span> and the server unless the client's
              request hasn't been completed yet.</p>

              <p>If the outgoing connection is idle, it will not be closed
              until either <span class="APPLICATION">Privoxy's</span> or the
              server's timeout is reached. While it's open, the server knows
              that the system running <span class=
              "APPLICATION">Privoxy</span> is still there.</p>

              <p>If there are more than one client (maybe even belonging to
              multiple users), they will be able to reuse each others
              connections. This is potentially dangerous in case of
              authentication schemes like NTLM where only the connection is
              authenticated, instead of requiring authentication for each
              request.</p>

              <p>If there is only a single client, and if said client can
              keep connections alive on its own, enabling this option has
              next to no effect. If the client doesn't support connection
              keep-alive, enabling this option may make sense as it allows
              <span class="APPLICATION">Privoxy</span> to keep outgoing
              connections alive even if the client itself doesn't support
              it.</p>

              <p>You should also be aware that enabling this option increases
              the likelihood of getting the "No server or forwarder data"
              error message, especially if you are using a slow connection to
              the Internet.</p>

              <p>This option should only be used by experienced users who
              understand the risks and can weight them against the
              benefits.</p>
            </dd>

            <dt>Examples:</dt>

            <dd>
              <p>connection-sharing 1</p>
            </dd>
          </dl>
        </div>
      </div>

      <div class="SECT3">
        <h4 class="SECT3"><a name="SOCKET-TIMEOUT" id="SOCKET-TIMEOUT">7.6.7.
        socket-timeout</a></h4>

        <div class="VARIABLELIST">
          <dl>
            <dt>Specifies:</dt>

            <dd>
              <p>Number of seconds after which a socket times out if no data
              is received.</p>
            </dd>

            <dt>Type of value:</dt>

            <dd>
              <p><tt class="REPLACEABLE c3">Time in seconds.</tt></p>
            </dd>

            <dt>Default value:</dt>

            <dd>
              <p>None</p>
            </dd>

            <dt>Effect if unset:</dt>

            <dd>
              <p>A default value of 300 seconds is used.</p>
            </dd>

            <dt>Notes:</dt>

            <dd>
              <p>The default is quite high and you probably want to reduce
              it. If you aren't using an occasionally slow proxy like Tor,
              reducing it to a few seconds should be fine.</p>
            </dd>

            <dt>Examples:</dt>

            <dd>
              <p>socket-timeout 300</p>
            </dd>
          </dl>
        </div>
      </div>

      <div class="SECT3">
        <h4 class="SECT3"><a name="MAX-CLIENT-CONNECTIONS" id=
        "MAX-CLIENT-CONNECTIONS">7.6.8. max-client-connections</a></h4>

        <div class="VARIABLELIST">
          <dl>
            <dt>Specifies:</dt>

            <dd>
              <p>Maximum number of client connections that will be
              served.</p>
            </dd>

            <dt>Type of value:</dt>

            <dd>
              <p><tt class="REPLACEABLE c3">Positive number.</tt></p>
            </dd>

            <dt>Default value:</dt>

            <dd>
              <p>None</p>
            </dd>

            <dt>Effect if unset:</dt>

            <dd>
              <p>Connections are served until a resource limit is
              reached.</p>
            </dd>

            <dt>Notes:</dt>

            <dd>
              <p><span class="APPLICATION">Privoxy</span> creates one thread
              (or process) for every incoming client connection that isn't
              rejected based on the access control settings.</p>

              <p>If the system is powerful enough, <span class=
              "APPLICATION">Privoxy</span> can theoretically deal with
              several hundred (or thousand) connections at the same time, but
              some operating systems enforce resource limits by shutting down
              offending processes and their default limits may be below the
              ones <span class="APPLICATION">Privoxy</span> would require
              under heavy load.</p>

              <p>Configuring <span class="APPLICATION">Privoxy</span> to
              enforce a connection limit below the thread or process limit
              used by the operating system makes sure this doesn't happen.
              Simply increasing the operating system's limit would work too,
              but if <span class="APPLICATION">Privoxy</span> isn't the only
              application running on the system, you may actually want to
              limit the resources used by <span class=
              "APPLICATION">Privoxy</span>.</p>

              <p>If <span class="APPLICATION">Privoxy</span> is only used by
              a single trusted user, limiting the number of client
              connections is probably unnecessary. If there are multiple
              possibly untrusted users you probably still want to
              additionally use a packet filter to limit the maximal number of
              incoming connections per client. Otherwise a malicious user
              could intentionally create a high number of connections to
              prevent other users from using <span class=
              "APPLICATION">Privoxy</span>.</p>

              <p>Obviously using this option only makes sense if you choose a
              limit below the one enforced by the operating system.</p>
            </dd>

            <dt>Examples:</dt>

            <dd>
              <p>max-client-connections 256</p>
            </dd>
          </dl>
        </div>
      </div>

      <div class="SECT3">
        <h4 class="SECT3"><a name="HANDLE-AS-EMPTY-DOC-RETURNS-OK" id=
        "HANDLE-AS-EMPTY-DOC-RETURNS-OK">7.6.9.
        handle-as-empty-doc-returns-ok</a></h4>

        <div class="VARIABLELIST">
          <dl>
            <dt>Specifies:</dt>

            <dd>
              <p>The status code Privoxy returns for pages blocked with
              <tt class="LITERAL"><a href=
              "actions-file.html#HANDLE-AS-EMPTY-DOCUMENT" target=
              "_top">+handle-as-empty-document</a></tt>.</p>
            </dd>

            <dt>Type of value:</dt>

            <dd>
              <p><tt class="REPLACEABLE c3">0 or 1</tt></p>
            </dd>

            <dt>Default value:</dt>

            <dd>
              <p>0</p>
            </dd>

            <dt>Effect if unset:</dt>

            <dd>
              <p>Privoxy returns a status 403(forbidden) for all blocked
              pages.</p>
            </dd>

            <dt>Effect if set:</dt>

            <dd>
              <p>Privoxy returns a status 200(OK) for pages blocked with
              +handle-as-empty-document and a status 403(Forbidden) for all
              other blocked pages.</p>
            </dd>

            <dt>Notes:</dt>

            <dd>
              <p>This is a work-around for Firefox bug 492459: <span class=
              "QUOTE">" Websites are no longer rendered if SSL requests for
              JavaScripts are blocked by a proxy. "</span> (<a href=
              "https://bugzilla.mozilla.org/show_bug.cgi?id=492459" target=
              "_top">https://bugzilla.mozilla.org/show_bug.cgi?id=492459</a>)
              As the bug has been fixed for quite some time this option
              should no longer be needed and will be removed in a future
              release. Please speak up if you have a reason why the option
              should be kept around.</p>
            </dd>
          </dl>
        </div>
      </div>

      <div class="SECT3">
        <h4 class="SECT3"><a name="ENABLE-COMPRESSION" id=
        "ENABLE-COMPRESSION">7.6.10. enable-compression</a></h4>

        <div class="VARIABLELIST">
          <dl>
            <dt>Specifies:</dt>

            <dd>
              <p>Whether or not buffered content is compressed before
              delivery.</p>
            </dd>

            <dt>Type of value:</dt>

            <dd>
              <p><tt class="REPLACEABLE c3">0 or 1</tt></p>
            </dd>

            <dt>Default value:</dt>

            <dd>
              <p>0</p>
            </dd>

            <dt>Effect if unset:</dt>

            <dd>
              <p>Privoxy does not compress buffered content.</p>
            </dd>

            <dt>Effect if set:</dt>

            <dd>
              <p>Privoxy compresses buffered content before delivering it to
              the client, provided the client supports it.</p>
            </dd>

            <dt>Notes:</dt>

            <dd>
              <p>This directive is only supported if Privoxy has been
              compiled with FEATURE_COMPRESSION, which should not to be
              confused with FEATURE_ZLIB.</p>

              <p>Compressing buffered content is mainly useful if Privoxy and
              the client are running on different systems. If they are
              running on the same system, enabling compression is likely to
              slow things down. If you didn't measure otherwise, you should
              assume that it does and keep this option disabled.</p>

              <p>Privoxy will not compress buffered content below a certain
              length.</p>
            </dd>
          </dl>
        </div>
      </div>

      <div class="SECT3">
        <h4 class="SECT3"><a name="COMPRESSION-LEVEL" id=
        "COMPRESSION-LEVEL">7.6.11. compression-level</a></h4>

        <div class="VARIABLELIST">
          <dl>
            <dt>Specifies:</dt>

            <dd>
              <p>The compression level that is passed to the zlib library
              when compressing buffered content.</p>
            </dd>

            <dt>Type of value:</dt>

            <dd>
              <p><tt class="REPLACEABLE c3">Positive number ranging from 0 to
              9.</tt></p>
            </dd>

            <dt>Default value:</dt>

            <dd>
              <p>1</p>
            </dd>

            <dt>Notes:</dt>

            <dd>
              <p>Compressing the data more takes usually longer than
              compressing it less or not compressing it at all. Which level
              is best depends on the connection between Privoxy and the
              client. If you can't be bothered to benchmark it for yourself,
              you should stick with the default and keep compression
              disabled.</p>

              <p>If compression is disabled, the compression level is
              irrelevant.</p>
            </dd>

            <dt>Examples:</dt>

            <dd>
              <table class="c4" border="0" width="90%">
                <tr>
                  <td>
                    <pre class="SCREEN">
    # Best speed (compared to the other levels)
    compression-level 1
    # Best compression
    compression-level 9
    # No compression. Only useful for testing as the added header
    # slightly increases the amount of data that has to be sent.
    # If your benchmark shows that using this compression level
    # is superior to using no compression at all, the benchmark
    # is likely to be flawed.
    compression-level 0

</pre>
                  </td>
                </tr>
              </table>
            </dd>
          </dl>
        </div>
      </div>
    </div>

    <div class="SECT2">
      <h2 class="SECT2"><a name="WINDOWS-GUI" id="WINDOWS-GUI">7.7. Windows
      GUI Options</a></h2>

      <p><span class="APPLICATION">Privoxy</span> has a number of options
      specific to the Windows GUI interface:</p><a name="ACTIVITY-ANIMATION"
      id="ACTIVITY-ANIMATION"></a>

      <p>If <span class="QUOTE">"activity-animation"</span> is set to 1, the
      <span class="APPLICATION">Privoxy</span> icon will animate when
      <span class="QUOTE">"Privoxy"</span> is active. To turn off, set to
      0.</p>

      <p class="LITERALLAYOUT"><tt class="LITERAL">&nbsp;&nbsp;<span class=
      "emphasis EMPHASIS c2">activity-animation 1</span><br>
      &nbsp;&nbsp;&nbsp;</tt></p><a name="LOG-MESSAGES" id=
      "LOG-MESSAGES"></a>

      <p>If <span class="QUOTE">"log-messages"</span> is set to 1,
      <span class="APPLICATION">Privoxy</span> will log messages to the
      console window:</p>

      <p class="LITERALLAYOUT"><tt class="LITERAL">&nbsp;&nbsp;<span class=
      "emphasis EMPHASIS c2">log-messages 1</span><br>
      &nbsp;&nbsp;&nbsp;</tt></p><a name="LOG-BUFFER-SIZE" id=
      "LOG-BUFFER-SIZE"></a>

      <p>If <span class="QUOTE">"log-buffer-size"</span> is set to 1, the
      size of the log buffer, i.e. the amount of memory used for the log
      messages displayed in the console window, will be limited to
      <span class="QUOTE">"log-max-lines"</span> (see below).</p>

      <p>Warning: Setting this to 0 will result in the buffer to grow
      infinitely and eat up all your memory!</p>

      <p class="LITERALLAYOUT"><tt class="LITERAL">&nbsp;&nbsp;<span class=
      "emphasis EMPHASIS c2">log-buffer-size 1</span><br>
      &nbsp;&nbsp;&nbsp;</tt></p><a name="LOG-MAX-LINES" id=
      "LOG-MAX-LINES"></a>

      <p><span class="APPLICATION">log-max-lines</span> is the maximum number
      of lines held in the log buffer. See above.</p>

      <p class="LITERALLAYOUT"><tt class="LITERAL">&nbsp;&nbsp;<span class=
      "emphasis EMPHASIS c2">log-max-lines 200</span><br>
      &nbsp;&nbsp;&nbsp;</tt></p><a name="LOG-HIGHLIGHT-MESSAGES" id=
      "LOG-HIGHLIGHT-MESSAGES"></a>

      <p>If <span class="QUOTE">"log-highlight-messages"</span> is set to 1,
      <span class="APPLICATION">Privoxy</span> will highlight portions of the
      log messages with a bold-faced font:</p>

      <p class="LITERALLAYOUT"><tt class="LITERAL">&nbsp;&nbsp;<span class=
      "emphasis EMPHASIS c2">log-highlight-messages 1</span><br>
      &nbsp;&nbsp;&nbsp;</tt></p><a name="LOG-FONT-NAME" id=
      "LOG-FONT-NAME"></a>

      <p>The font used in the console window:</p>

      <p class="LITERALLAYOUT"><tt class="LITERAL">&nbsp;&nbsp;<span class=
      "emphasis EMPHASIS c2">log-font-name Comic Sans MS</span><br>
      &nbsp;&nbsp;&nbsp;</tt></p><a name="LOG-FONT-SIZE" id=
      "LOG-FONT-SIZE"></a>

      <p>Font size used in the console window:</p>

      <p class="LITERALLAYOUT"><tt class="LITERAL">&nbsp;&nbsp;<span class=
      "emphasis EMPHASIS c2">log-font-size 8</span><br>
      &nbsp;&nbsp;&nbsp;</tt></p><a name="SHOW-ON-TASK-BAR" id=
      "SHOW-ON-TASK-BAR"></a>

      <p><span class="QUOTE">"show-on-task-bar"</span> controls whether or
      not <span class="APPLICATION">Privoxy</span> will appear as a button on
      the Task bar when minimized:</p>

      <p class="LITERALLAYOUT"><tt class="LITERAL">&nbsp;&nbsp;<span class=
      "emphasis EMPHASIS c2">show-on-task-bar 0</span><br>
      &nbsp;&nbsp;&nbsp;</tt></p><a name="CLOSE-BUTTON-MINIMIZES" id=
      "CLOSE-BUTTON-MINIMIZES"></a>

      <p>If <span class="QUOTE">"close-button-minimizes"</span> is set to 1,
      the Windows close button will minimize <span class=
      "APPLICATION">Privoxy</span> instead of closing the program (close with
      the exit option on the File menu).</p>

      <p class="LITERALLAYOUT"><tt class="LITERAL">&nbsp;&nbsp;<span class=
      "emphasis EMPHASIS c2">close-button-minimizes 1</span><br>
      &nbsp;&nbsp;&nbsp;</tt></p><a name="HIDE-CONSOLE" id=
      "HIDE-CONSOLE"></a>

      <p>The <span class="QUOTE">"hide-console"</span> option is specific to
      the MS-Win console version of <span class="APPLICATION">Privoxy</span>.
      If this option is used, <span class="APPLICATION">Privoxy</span> will
      disconnect from and hide the command console.</p>

      <p class="LITERALLAYOUT"><tt class="LITERAL">&nbsp;&nbsp;#<span class=
      "emphasis EMPHASIS c2">hide-console</span><br>
      &nbsp;&nbsp;&nbsp;</tt></p>
    </div>
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